21019820117 has 2 divisors, whose sum is σ = 21019820118. Its totient is φ = 21019820116.

The previous prime is 21019820089. The next prime is 21019820123. The reversal of 21019820117 is 71102891012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20901641476 + 118178641 = 144574^2 + 10871^2 .

It is a cyclic number.

It is not a de Polignac number, because 21019820117 - 2⁸ = 21019819861 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21019820917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10509910058 + 10509910059.

It is an arithmetic number, because the mean of its divisors is an integer number (10509910059).

Almost surely, 2^21019820117 is an apocalyptic number.

It is an amenable number.

21019820117 is a deficient number, since it is larger than the sum of its proper divisors (1).

21019820117 is an equidigital number, since it uses as much as digits as its factorization.

21019820117 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2016, while the sum is 32.

The spelling of 21019820117 in words is "twenty-one billion, nineteen million, eight hundred twenty thousand, one hundred seventeen".